Abstract: A method for fabricating high electron mobility transistor (HEMT) includes the steps of: forming a first barrier layer on a substrate; forming a p-type semiconductor layer on the first barrier layer; forming a hard mask on the p-type semiconductor layer; patterning the hard mask and the p-type semiconductor layer; and forming a spacer adjacent to the hard mask and the p-type semiconductor layer.

Abstract: A mesa structure includes a substrate. A mesa protrudes out of the substrate. The mesa includes a slope and a top surface. The slope surrounds the top surface. A lattice damage area is disposed at inner side of the slope. The mesa can optionally further includes an insulating layer covering the lattice damage area. The insulating layer includes an oxide layer or a nitride layer.

Abstract: A high-electron mobility transistor includes a substrate; a buffer layer over the substrate; a GaN channel layer over the buffer layer; a AlGaN layer over the GaN channel layer; a gate recess in the AlGaN layer; a source region and a drain region on opposite sides of the gate recess; a GaN source layer and a GaN drain layer grown on the AlGaN layer within the source region and the drain region, respectively; and a p-GaN gate layer in and on the gate recess.

Abstract: A high-electron mobility transistor includes a substrate; a buffer layer on the substrate; a AlGaN layer on the buffer layer; a passivation layer on the AlGaN layer; a source region and a drain region on the AlGaN layer; a source layer and a drain layer on the AlGaN layer within the source region and the drain region, respectively; a gate on the AlGaN layer between the source region and a drain region; and a field plate on the gate and the passivation layer. The field plate includes an extension portion that laterally extends to an area between the gate and the drain region. The extension portion has a wave-shaped bottom surface.

Abstract: A high-electron mobility transistor includes a substrate; a buffer layer on the substrate; a AlGaN layer on the buffer layer; a passivation layer on the AlGaN layer; a source region and a drain region on the AlGaN layer; a source layer and a drain layer on the AlGaN layer within the source region and the drain region, respectively; a gate on the AlGaN layer between the source region and a drain region; and a field plate on the gate and the passivation layer. The field plate includes an extension portion that laterally extends to an area between the gate and the drain region. The extension portion has a wave-shaped bottom surface.

Abstract: A method of forming an insulating structure of a high electron mobility transistor (HEMT) is provided, the method including: forming a gallium nitride layer, forming an aluminum gallium nitride layer on the gallium nitride layer, performing an ion doping step to dope a plurality of ions in the gallium nitride layer and the aluminum gallium nitride layer, forming an insulating doped region in the gallium nitride layer and the aluminum gallium nitride layer, forming two grooves on both sides of the insulating doped region, and filling an insulating layer in the two grooves and forming two sidewall insulating structures respectively positioned at two sides of the insulating doped region.

Abstract: A method for fabricating high electron mobility transistor (HEMT) includes the steps of: forming a buffer layer on a substrate; forming a first barrier layer on the buffer layer; forming a first hard mask on the first barrier layer; removing the first hard mask and the first barrier layer to form a recess; forming a second barrier layer in the recess; and forming a p-type semiconductor layer on the second barrier layer.

Abstract: A high electron mobility transistor (HEMT) includes a substrate; a buffer layer over the substrate, a GaN layer over the buffer layer, a first AlGaN layer over the GaN layer, a first AlN layer over the AlGaN layer, and a p-GaN layer over the first AlN layer.

Abstract: According to an embodiment of the present invention, a method for fabricating high electron mobility transistor (HEMT) includes the steps of: forming a buffer layer on a substrate; forming a first barrier layer on the buffer layer; forming a second barrier layer on the first barrier layer; forming a first hard mask on the second barrier layer; removing the first hard mask and the second barrier layer to form a recess; and forming a p-type semiconductor layer in the recess.

Abstract: A semiconductor device includes an enhancement mode high electron mobility transistor (HEMT) with an active region and an isolation region. The HEMT includes a substrate, a group III-V body layer, a group III-V barrier layer and a recess. The group III-V body layer is disposed on the substrate. The group III-V barrier layer is disposed on the group III-V body layer in the active region and the isolation region. The recess is disposed in the group III-V barrier layer in the active region.

Abstract: A semiconductor device includes an enhancement mode high electron mobility transistor (HEMT) with an active region and an isolation region. The HEMT includes a substrate, a group III-V body layer, a group III-V barrier layer, a group III-V gate structure and a group III-V patterned structure. The group III-V body layer and the group III-V barrier layer are disposed on the substrate. The group III-V gate structure is disposed on the group III-V barrier layer within the active region. The group III-V patterned structure is disposed on the group III-V barrier layer within the isolation region. The composition of the group III-V patterned structure is the same as the composition of the group III-V gate structure.

Abstract: A method of forming an insulating structure of a high electron mobility transistor (HEMT) is provided, the method including: forming a gallium nitride layer, forming an aluminum gallium nitride layer on the gallium nitride layer, performing an ion doping step to dope a plurality of ions in the gallium nitride layer and the aluminum gallium nitride layer, forming an insulating doped region in the gallium nitride layer and the aluminum gallium nitride layer, forming two grooves on both sides of the insulating doped region, and filling an insulating layer in the two grooves and forming two sidewall insulating structures respectively positioned at two sides of the insulating doped region.

Abstract: An enhancement mode high electron mobility transistor (HEMT) includes a group III-V semiconductor body, a group III-V barrier layer and a gate structure. The group III-V barrier layer is disposed on the group III-V semiconductor body, and the gate structure is a stacked structure disposed on the group III-V barrier layer. The gate structure includes a gate dielectric and a group III-V gate layer disposed on the gate dielectric, and the thickness of the gate dielectric is between 15 nm to 25 nm.

Abstract: A high electron mobility transistor (HEMT) includes a substrate; a buffer layer over the substrate, a GaN layer over the buffer layer, a first AlGaN layer over the GaN layer, a first AlN layer over the AlGaN layer, and a p-GaN layer over the first AlN layer.

Abstract: An HEMT includes a first III-V compound layer. A second III-V compound layer is disposed on the first III-V compound layer. The composition of the first III-V compound layer and the second III-V compound layer are different from each other. A source electrode and a drain electrode are disposed on the second III-V compound layer. The gate electrode is disposed on the second III-V compound layer between the source electrode and the drain electrode. An insulating layer is disposed between the drain electrode and the gate electrode and covers the second III-V compound layer. At least one electrode is disposed on the insulating layer and contacts the insulating layer, wherein a voltage is applied to the electrode.

Abstract: An insulating structure of a high electron mobility transistor (HEMT) is provided, which comprises a gallium nitride layer, an aluminum gallium nitride layer disposed on the gallium nitride layer, a groove disposed in the gallium nitride layer and the aluminum gallium nitride layer, an insulating layer disposed in the groove, wherein a top surface of the insulating layer is aligned with a top surface of the aluminum gallium nitride layer, and a passivation layer, disposed on the aluminum gallium nitride layer and the insulating layer.

Abstract: An insulating structure of a high electron mobility transistor (HEMT) is provided, which comprises a gallium nitride layer, an aluminum gallium nitride layer disposed on the gallium nitride layer, an insulating doped region disposed in the gallium nitride layer and the aluminum gallium nitride layer, and two sidewall insulating structures disposed at two sides of the insulating doped region respectively.

Abstract: A method for fabricating high electron mobility transistor (HEMT) includes the steps of: forming a buffer layer on a substrate; forming a barrier layer on the buffer layer; forming a hard mask on the barrier layer; performing an implantation process through the hard mask to form a doped region in the barrier layer and the buffer layer; removing the hard mask and the barrier layer to form a first trench; forming a gate dielectric layer on the hard mask and into the first trench; forming a gate electrode on the gate dielectric layer; and forming a source electrode and a drain electrode adjacent to two sides of the gate electrode.

Abstract: An insulating structure of a high electron mobility transistor (HEMT) is provided, which comprises a gallium nitride layer, an aluminum gallium nitride layer disposed on the gallium nitride layer, an insulating doped region disposed in the gallium nitride layer and the aluminum gallium nitride layer, and two sidewall insulating structures disposed at two sides of the insulating doped region respectively.

Abstract: A semiconductor epitaxial structure with reduced defects, including a substrate with a recess formed thereon, an island insulator on a bottom surface of the recess, spacers on sidewalls of the recess, a buffer layer in the recess and covering the island insulator, a channel layer in the recess and on the buffer layer, and a barrier layer in the recess and on the channel layer, wherein two-dimensional electron gas (2DEG) or two-dimensional hole gas (2DHG) is formed in the channel layer.